Object Indexes and the Launching Effect

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How to get beyond intuition?

The launching effect: detecting a 50ms difference in the delay between two movements.

How is launching detected? For example, does it involve perceptual processes?
Why is a delay of up to around 70ms consistent with the launching effect occuring?

Ok, but what is the nature of these perceptual processes? Object indexes ...

object indexes require tracking some causal interactions ...

But before we get to that, what is this about causal interactions? It's reasonably obvious that object indexes require segmentation (otherwise how would they attach to *objects*), and the evidence that they can survive occlusion is relatively easy to understand. But the point that having object indexes involves tracking causal interactions is less straightforward. So let's consider that ...

Object indexes are linked to causation. In order to track objects, a perceptual system has to be sensitive to be causal interactions

Why is this true? Because when you have a causal interaction, there's a conflict between principles of object perception e.g. distinct surfaces=>two objects, vs good continuity of motion=>one object The perceptual system needs to know when conflicts should be reconciled and when they should be written off. We get perceptual effects of causal interactions when there are conflicts among cues of object identity.

This is a point Michotte made. He found that launching occurs when there is a conflict between cues to object identity: good continuity of movement suggests a single object whereas the existence of two distinct surfaces indicates two objects.

It is plausible that other types of causal interaction also involve conflicts between cues to object identity.

preliminary evidence

Kruschke and Fragassi, 1996 figure 2 (part)

Krushke and Fragassi (1996) have shown that the object-specific preview effect vanishes in launching but not in various spatio-temporally similar sequences. Since the object-specific preview effect is regarded as diagnostic of feature binding, this is evidence that in launching sequences, features of the second object (such as motion) remain bound to the first object for a short time after the second object starts to move.

Kruschke and Fragassi, 1996 figure 2

Kruschke and Fragassi, 1996 figure 3

‘Unfortunately, this preliminary study has not received any published follow-up work, to our knowledge, so it is not clear if it would also generalize beyond highly specific contrasts.’

\citep{choi:2006_measuring} on Kruschke and Fragassi: ‘one previous study suggested that causal events gave rise to diVerent patterns of object-specific priming than non-causal events (Kruschke & Fragassi, 1996). Unfortunately, this preliminary study has not received any published follow-up work, to our knowledge, so it is not clear if it would also generalize beyond highly specific contrasts’ \citep[p.~108]{choi:2006_measuring}.

Choi & Scholl, 2006 p. 108

This finding fits (by design) almost perfectly with Michotte’s phenomenological analysis ...

‘the movement performed by object B appears simultaneously under two different guises: (i) as a movement (belonging to object A), (ii) as a change in relative position (by object B)’

\citep[p.~136]{Michotte:1946nz}

Michotte 1946 [1963], p. 136

‘the physical movement of the object struck gives rise to a double representation. This movement appears at one and the same time (a) as a continuation of the previous movement of the motor object, and (b) as a change of relative position (a purely spatial withdrawal) of the projectile in relation to the motor object.’

\citep[p.~140]{Michotte:1946nz}

Michotte 1946 [1963], p. 140

\emph{Causal Object Index Conjecture}:

Causal Object Index Conjecture:

Effects associated with the ‘perception of causation’ are consequences of errors (or error-like patterns) in the assignments of object indexes and their phenomenal effects.

Predictions:

i. Where there is perception of causation, there will be errors (or error-like patterns) in the assignments of object indexes.

ii. Factors that can influence how object indexes are assigned or maintained can influence perception of causation.

There is already some evidence which hints at this ...

The conditions that affect launching are consistent with it being a consequence of how object indexes are updated and maintained ...

‘Michotte and his followers worked out many of the factors which mediate the perception of causality, such as the role of absolute and relative speeds, spatial and temporal gaps in the objects' trajectories, differences in the durations and angles of each object's trajectory, etc ...

‘This research has generally shown that many different spatiotemporal parameters are critical for perceiving causality, but that featural parameters (eg colors, shapes, sizes) play little or no role.’

\citep[p.~456]{Scholl:2004dx}

Scholl and Nakayama 2004, p. 456

Assignments of object indexes are not generally sensitive to featural information (*check: perceiving expressions of emotion paper / dev.mind).

Scholl 2007, figure 4

Causal Object Index Conjecture:

Effects associated with the ‘perception of causation’ are consequences of errors (or error-like patterns) in the assignments of object indexes and their phenomenal effects.

Predictions:

i. Where there is perception of causation, there will be errors (or error-like patterns) in the assignments of object indexes.

ii. Factors that can influence how object indexes are assigned or maintained can influence perception of causation.

There is even more evidence which hints at this ...

If you've read Rips (2011) you’ll know about dissociations between the launching effect and causal reasoning.

dissociations between the launching effect and causal reasoning (Rips 2011)

Schlottmann and Shanks (1992, Experiment 2) ... The point of this experiment was to distinguish between cues to causality provided by perceptual features within a display (launching vs. delay) and by statistical contingencies (between Object A moving and Object B moving) as observed across trials. If Michotte’s hypothesis is correct, statistical contingencies should not affect perceptual judgments of whether a launching has occurred. Conversely, perceptual features should not affect judgments of whether A’s movement is statistically necessary for B’s movement. ... The results of the study were clear cut ...: Launching versus delay affected ratings of how convincing the collisions looked but not ratings of necessity. However, the presence of a predictive statistical relation affected ratings of necessity but not ratings of convincingness. These results are consistent with Michotte’s hypothesis: Statistical contingencies over trials do not affect the cause detector on the right of Figure 3A, which is sensitive only to purely spatio-temporal properties of the individual displays. \citep[p.~87]{rips:2011_causation}

Schlottman & Shanks (1992, p. 340): ‘Despite the fact that a colour change of Object B more reliably predicted B’s movement than did the impact of Object A, where was no impact of the predictive relationship on subjects’ ratings of perceived causality. In other experiments asking subjects to make causal judgements, however, such alternative predictive signals are known to reduce subjects’ ratings dramatically (Shanks, 1986).’

‘The clearest dissociation among the neuropsychology studies comes from Roser, Fugelsang, Dunbar, Corballis, and Gazzaniga (2005), who tested two split-brain patients. ... The patients were able to discriminate the launching sequence from the others only if their right hemisphere processed the event. By contrast, the same patients were able to solve a causal reasoning problem—figuring out which of two switches controlled a light—only if the problem appeared to their left hemisphere.’ \citep[p.~88]{rips:2011_causation}

Causal Object Index Conjecture:

Effects associated with the ‘perception of causation’ are consequences of errors (or error-like patterns) in the assignments of object indexes and their phenomenal effects.

Predictions:

i. Where there is perception of causation, there will be errors (or error-like patterns) in the assignments of object indexes.

ii. Factors that can influence how object indexes are assigned or maintained can influence perception of causation.

Causal Object Index Conjecture:

Effects associated with the ‘perception of causation’ are consequences of errors (or error-like patterns) in the assignments of object indexes and their phenomenal effects.

Potential objections:

i. Adaptation effects [see appendix]

ii. Rips-Leslie argument from the Pulfrich double-pendulum illusion [see appendix]

How to get beyond intuition?

The launching effect: detecting a 50ms difference in the delay between two movements.

How is launching detected? For example, does it involve perceptual processes?
Why is a delay of up to around 70ms consistent with the launching effect occuring?

Very good, but what does this tell us about the question with which I started? I.e. can humans perceive causal interactions?

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Object Indexes and the Launching Effect

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